Abstract: A process is disclosed for the long term surviving culture of hepatocytes maintaining their morphological and functional characteristics for long-term periods, suitable to assest the acute and chronic hepatotoxicity of drugs, chemicals and environmental pollutants. The long term surviving culture of hepatocytes is carried out in a culture media containing fibroblast cells or fibroblast cell products treated to prevent cell multiplication and inoculated under controlled density.

Abstract: A method for decontaminating cell cultures comprising contacting cell cultures with quinolone- and 1,8-naphthyridonecarboxylic acids of the formula (I) ##STR1## in which R.sup.1 represents methyl, ethyl, propyl, isopropyl, cyclopropyl, vinyl, 2-hydroxyethyl, 2-fluorethyl, methoxy, amino, methylamino, dimethylamino, ethylamino, phenyl, 4-fluorophenyl or 2,4-difluorophenyl,R.sup.2 represents hydrogen, alkyl having 1 to 4 carbon atoms, or (5-methyl-2-oxo-1,3-dioxol-4-yl)-methyl,R.sup.3 represents methyl or a cyclic amino group such as ##STR2## in which R.sup.4 represents hydrogen, alkyl having 1 to 4 carbon atoms, 2-hydroxyethyl, allyl, propargyl, 2-oxopropyl, 3-oxobutyl, phenacyl, formyl, CFCl.sub.2 --S--, CFCl.sub.2 --SO.sub.2 --, CH.sub.3 O--CO--S--, benzyl, 4-aminobenzyl or ##STR3## R.sup.5 represents hydrogen or methyl, R.sup.6 represents hydrogen, alkyl having 1 to 4 carbon atoms, phenyl or benzyloxomethyl,R.sup.